The present invention is generally related to the field of data communications and, more particularly, is related to a system and method for transmitting a facsimile via a network.
The use of facsimile machines that link up with each other by way of the public switched telephone network (PSTN) has become wide spread around the world. Data transmission by facsimile is generally asymmetric in that most of the data transfer flows in one direction, namely, from the transmitting facsimile to the receiving facsimile. Transmission in the reverse direction is minimal and generally encompasses acknowledgement signals from the receiving facsimile to the transmitting facsimile. One common problem with transmission by facsimile using the PSTN is that it often requires long distance telephone calls between facsimile machines.
With the onset of the Internet, new modes of data transfer are possible that eliminate the problem of long distance telephone calls. Specifically, current efforts have been undertaken to allow facsimile machines to use the Internet to transfer data where the respective facsimile machines link up locally to the Internet using the PSTN. For example, a calling facsimile machine contacts a first gateway via a local call over the PSTN. The first gateway then communicates with a second gateway over the Internet. The second gateway the contacts the receiving facsimile machine via a local call over the PSTN. Essentially, the Internet is used as a tool to avoid long distance communication between facsimile machines. Such data transfer is often referred to as xe2x80x9cFaxover Internet Protocolxe2x80x9d or xe2x80x9cFaxover IPxe2x80x9d.
Unfortunately, the Internet is capable of transmitting data much faster than the data communication that takes place between the facsimile machines and their respective gateways over the public switched telephone network. In a sense, the facsimile machines become a bottleneck that significantly reduces the speed at which a facsimile is transferred using Faxover IP approaches.
In light of the foregoing, the present invention provides for a data communications system and method in a facsimile machine to establish a data link with a gateway over a local loop. The data link is established employing pulse code modulation with prioritization in the upstream direction. Alternatively, a modulation type may be employed that is equivalent to pulse code modulation that provides similar or higher speed data communication. By using pulse code modulation in the upstream direction, the resulting facsimile transmission in accomplished with much greater speed.
In one embodiment, the present system may include, for example, a processor circuit having a processor and a memory that are coupled to a local interface such as, for example, a data bus with an accompanying control bus. Also, the system includes data communications logic stored on the memory and executable by the processor. To begin, the data communications logic is executed, for example, to set-up a virtual data communications link with a peer facsimile machine through a first public switched telephone network (PSTN) link, a network, and a second PSTN link. Once the virtual data communications link is established, then a data rate is negotiated with the peer facsimile. The negotiations performed determine whether the peer facsimile is capable of employing pulse code modulation or its equivalent. Finally, a facsimile transmission is performed in which the upstream data signal in the first PSTN link is sent using a pulse code modulation.
The present system may also be viewed as a method for data communication in a facsimile machine. In this regard, the method includes the steps of: setting up a virtual data communications link with a peer facsimile machine through a first public switched telephone network (PSTN) link, a network, and a second PSTN link; negotiating a data rate with the peer facsimile; and transmitting an upstream data signal in the first PSTN link using a pulse code modulation.
Other features and advantages of the present invention will become apparent to a person with ordinary skill in the art in view of the following drawings and detailed description. It is intended that all such additional features and advantages be included herein within the scope of the present invention.